1. Field of the Invention
The present invention is directed to a connection arrangement for coupling a hydrodynamic torque converter to a rotating shaft so that the hydrodynamic torque converter is fixed with respect to rotation relative to the rotating shaft, the connection arrangement comprising at least one fastening element arranged at a converter housing of the torque converter.
2. Description of the Related Art
A prior art connection arrangement for connecting a hydrodynamic torque converter to a rotating shaft is known, for example, from German reference DE 44 24 989 A1. The accompanying FIG. 3 shows a torque converter 110 with a converter housing 112 having a housing cover 134. A turbine wheel 114xe2x80x94shown schematicallyxe2x80x94is arranged in the interior of the converter housing 112 so that the turbine wheel 114 is rotatable relative to the converter housing 112. The turbine wheel 114 has a turbine wheel shell 116 and a turbine wheel hub 118 that is coupled or can be coupled in a manner known per se with a driven shaft such, for example, as a transmission input shaft 120, so that it is fixed with respect to rotation relative to the driven shaft. The torque converter 110 also has a lockup clutch 122 with a clutch piston 124 which is displaceable in the axial direction and has a radial outer area 126 on which a friction facing 128 may be arranged which can be pressed against a substantially flat friction surface area 130 at an inner surface 132 of the housing cover 134 of the converter housing 112. Further, a centering pin 136 is secured to the housing cover 134 such, for example, as by welding. The centering pin 136 engages in a centering opening 138 of a rotating shaft 140xe2x80x94shown schematicallyxe2x80x94and accordingly provides a centering of the torque converter 110 with respect to this rotating shaft 140. The rotating shaft 140 may, for example, comprise a crankshaft of an internal combustion engine. A plurality of fastening elements 44 are secured successively along a circumferential direction about the axis of rotation A by a weld to an outer surface 142 of the converter housing 112 which faces in the axial direction toward the rotating shaft 140. These fastening elements 144 are nut elements with an internal thread 146.
FIG. 3 also shows a connection plate 148 such, for example, as a flex-plate which has openings 150 in a radial inner area. The openings 150 may be penetrated by screw bolts, not shown, to secure the connection plate 148 to the rotating shaft 140. A radially outer area of the connection plate 148 also has an opening 152 associated with each fastening element 144 and through which screws may be screwed into the fastening elements 144 to join the converter housing 112 to the rotating shaft 140 such that it is fixed with respect to rotation relative to it.
In this type of connection arrangement, in which the fastening elements 144 are secured to the converter housing 112 by welding, subsequent machining steps are required after this welding process is carried out to restore the converter housing 112, i.e., the cover 134 thereof, to its desired shape. Welding is prized in the automotive industry for its excellent connection stability. However, because of the heat introduced into the material of the housing cover 134 during the welding process, the housing cover 134 is at least slightly warped. Even the slightest warp cannot be tolerated because housing cover 134 forms the counter-friction surface 130 for the lockup clutch 122. Therefore, a cutting machining step is required to restore exact true running of the cover 134 and housing 112. This cutting machining step increases the number of necessary work steps and impairs strength especially in the region of the surface of the converter housing 112.
It is the object of the present invention to provide a connection arrangement for coupling a hydrodynamic torque converter to a rotating shaft such that the hydrodynamic torque converter is fixed with respect to rotation relative to the rotating shaft and so that the integrity of the torque converter is not impaired, especially in the region of the converter housing, during the connection process.
According to an embodiment of the present invention, this object is met by a connection arrangement for coupling a hydrodynamic torque converter to a rotating shaft so as to be fixed with respect to rotation relative to it, wherein the connection arrangement comprises at least one fastening element arranged at a converter housing. The at least one fastening element is arranged at the converter housing in that an engagement portion of the at least one fastening element meshes in a positive engagement with a receiving portion of the converter housing.
Accordingly, the present invention produces a positive-locking connection in lieu of the known method of connecting the fastening element and converter housing in a material engagement by welding. As a result, the present invention eliminates the introduction of heat into the material of the converter housing that is required for achieving the material-engagement welding connection. Consequently, the connection arrangement according to the invention does not impair the operating behavior or the integrity of the torque converter in the area of the housing of the torque converter, thereby eliminating the requirement for any additional subsequent machining processes for removing the impermissible deformations of the converter housing caused by the connection process.
In the connection arrangement according to the invention, at least one positive engagement acting in the direction of the rotating shaft is preferably generated between the fastening portion of the at least one fastening element and the fastening portion of the converter housing. For example, the fastening portion of the converter housing may comprise a receiving recess and the fastening portion of the at least one fastening element may comprise an engagement portion which is insertable into the receiving recess.
In a preferred embodiment, the engagement portion of the at least one fastening element is constructed so that it widens toward its free end and has a maximum outer dimensioning, i.e., an outer diameter, which allows for the insertion of the engagement portion into the receiving recess. That is, the engagement portion has a tapering with an increasing diameter toward its free end. Furthermore, a deformation area is provided at the at least one fastening element, wherein, when the engagement portion engages at least partially in the receiving recess, the deformation area acts in at least some areas on the material area of the converter housing surrounding the receiving recess and deforms this material area in such a way that it engages behind the tapering engagement portion. Accordingly, it is necessary only to push the engagement portion of the at least one fastening element into the respective receiving recess and to press the fastening element into this receiving recess, wherein the positive engagement arrangement is formed automatically due to the configuration of the fastening element.
To minimize the impairment to the stability of the converter housing and to prevent the occurrence of sealing problems in the torque converter, the receiving recess associated with the at least one fastening element comprises a recess in the form of a pocket hole which is open toward the outside of the converter housing.
To achieve a stable positive-locking engagement, the at least one fastening element may be formed from metal, sintered material or a combination material, for example, a rubber-metal combination.
Further, the connection arrangement according to the invention may comprise a plurality of fastening elements arranged successively in a circumferential direction about an axis of rotation.
The present invention is also directed to a hydrodynamic torque converter with the connection arrangement described above.
The present invention is also directed to a process for providing a connection arrangement at a hydrodynamic torque converter, wherein the process comprises the following steps:
a) providing at least one receiving recess at an outer surface of a converter housing;
b) inserting an engagement portion of a fastening element into the receiving recess, which engagement portion includes a tapered portion that widens toward a free end; and
c) causing a deformation of a material area of the converter housing surrounding at least one receiving recess after at least partial insertion of the engagement portion in the receiving recess, which deformation is carried out such that the material area engages behind the tapered portion, thereby creating the positive-locking engagement.
Step a) includes providing the at least one receiving recess by pressing, stamping or the like.
Further, in the process according to the invention, step c) may comprise pressing the fastening element into the receiving recess and, in so doing, deforming the material area of the converter housing surrounding the receiving recess by a deformation area provided at the fastening element.
The process according to the invention is preferably performed for a plurality of receiving recesses.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.